Imines, their preparation and their pharmaceutical use

ABSTRACT

Imines of 2-formylquinoxaline-3-carboxylic acid-1,4-dioxides and their salts are obtained through treatment of the lactone or a salt of 2-dihydroxymethylquinoxaline-N,N-dioxide-3-carboxylic acid with a reactant bearing a free primary amino group. The resultant compounds and their non-toxic salts are antibacterial agents and can be incorporated in pharmaceutical compositions and feedstuffs for this use. A typical embodiment is 2(carbomethoxyhydrazonomethyl)-quinoxaline-3-carboxylic acid-1,4dioxide.

United States Patent 1191 Seng et al.

1451 Feb. 4, 1975 IMINES, TIIEIR PREPARATION AND THEIR PHARMACEUTICAL USE [75] Inventors: Florin Seng, Koln-Buchheim; Kurt Ley, Odenthal-Globusch; Karl Georg Metzger, Wuppertal-Elberfeld, all of Germany [73] Assignee: Bayer Aktiengesellschaft,

Leverkusen, Germany [22] Filed: May 11,1973

[21] Appl. No.: 359,308

Related US. Application Data [62] Division of Ser. No. 130,007, March 31, 1971.

[301 Foreign Application Priority Data Apr. 2, 1970 Germany 2015676 [52] US. Cl. 260/240 G, 99/2 M, 99/4,

424/250, 260/250 Q, 260/250 ON [51] Int. Cl C07d 51/78 [58] Field of Search 260/240 G, 250 Q. 250 ON 156] References Cited UNITED STATES PATENTS 3,371,090 2/1968 Johnston 260/240 (i 3,493,572 2/1970 Johnston. 260/251) ()N 3,793,323 2/1974 Seng et ailv 260/2515 FOREIGN PATENTS OR APPLICATIONS 7,104,392 10/1971 Netherlands 260/240 (1 Primary Examiner-John D. Randolph 12 Claims, No Drawings 'i ll COOY 1 (In H i CH:N-R 0 wherein Y is hydrogen, an alkali metal cation or the cation R"N"H;,; and

each of R and R" is identical to or different from the other and is selected from the group consisting of a. alkyl, substituted alkyl or cycloalkyl;

in which each of R and R when taken independently is identical to or different from the other, and is selected from the group consisting of hydrogen, alkyl or substituted alkyl, or when R and R are taken together with the nitrogen atom to which they are attached a to 7-membered heterocyclic ring optionally containing as a ring member oxygen, sulphur, S0: or N-alkyl;

-Nnon in which X is O. S or NH and, R and R are as above defined;

-NH-C-OR in which R is alkyl or substituted alkyl;

-NH-C-R in which R is phenyl. pyridy'l or norbornyl. and X is as defined above:

NR i! NH N\R2 in which R, R and X are as defined above: or

r H N N E NU A preferred group of the imines and salts of the in vention are those of the above general formula I J. in which:

Y has the meanings given above; each of R and R is identical to or different from the other and is selected from the group consisting of a. alkyl or hydroxyalkyl of from I to 4 carbon atoms or a o-membered or 7-membered monocycloor bicycloalkyl group;

in which each of R and R when taken independently is identical to or different from the other and is selected from the group consisting ofhydrogen. alkyl or hydroxyalkyl of from I to 4 carbon atoms, or when R and R are taken together with the nitrogen atom to which they are attached. a (J-membered heterocyclic ring optionally containing as a ring member oxygen or 50 -NH-CIN in which X is O. S or NH, and R and R are as herein in which R" is alkyl or hydroxyalkyl of from I to 4 carbon atoms; and

(c) awe-n in which R is phenyl. pyridyl or norbornyl and X is as herein defined.

Aliphatic groups embraced by R and R include straightchain or branched alkyl groups of from 1 to 6. preferably 1 to 4, carbon atoms. Cyeloaliphatic radicals contain from 3 to 7. preferably 5 to 7. carbon atoms and include both monocyclic and bicyclic ring systems.

These aliphatic or cycloaliphatic groups can be optionally substituted. for example. by hydroxy. alkoxy. or acyloxy. the alkoxy and acyloxy groups containing l to 4. preferably l or 2. carbon atoms. The hydroxy group is the preferred substituent. Typical aliphatic and cycloaliphatic groups thus include methyl. ethyl. npropyl, isopropyl. n-butyl, isobutyl. ter.-butyl. n-pcntyl. isopentyl. hexyl, Z-hydroxyethyl. cyclopropyl, cyclopentyl. cyclohexyl, bicyclo-(2.2.l l-heptyl (norbornyl). and the like.

The substituents R' and R are hydrogen or alkyl of from I to 4. preferably l or 2, carbon atoms. These alkyl groups can be optionally substituted with hydroxy. alkoxy or acyloxy. alkoxy and acyloxy groups containing l to 4. preferably l or 2, carbon atoms. Thus included are ethyl. n-propyl, isopropyl, n-butyl. isobutyl and tert.-butyl, as well as the corresponding groups substituted by hydroxy.

R and R when taken together with the nitrogen atom to which they are attached, can also form a heterocyclic ring. preferably containing 6 ring members. and preferably with an oxygen atom, a sulphur atom. an N- alkyl group containing 1 to 4, preferably l or 2, carbon atoms. or the S group. as a ring member in the pposition relative to the nitrogen atom to which R and R are attached.

R is an alkyl offrom l to 4. preferably l or 2. carbon atoms which may also be optionally substituted by hydroxy. alkoxy, acyloxy. alkoxy and acyloxy containing l to 4. preferably 1 or 2, carbon atoms. The hydroxy group is a particularly preferred substituent. R thus embraces such groups as methyl. ethyl. Z-hydroxyethyl and the like.

The alkali metal cation Y is. for example. that of sodium or potassium, preferably that of sodium.

R is phenyl. pyridyl or norborn-Z-yl. When R is pyridyl. it can be bonded in the 2-, 3- or 4-position relative to the pyridyl nitrogen atom.

The above class of imines are obtained according to the process of the present invention by treatment of l oxo-3-hydroxy-l .3-dihydro-furo-l 3.4-bl-quinoxaline- 4.9dioxide, which has the formula:

all

or a salt thereof of the formula:

coo

H tr l \on 0 x with an amine of the general formula HgN'R. in which R is as previously defined. M is an alkali metal or alkaline earth metal cation and x is l or 2.

The salts ofthe formula can be obtained from the lactone of formula through treatment with alkali metal or alkaline earth metal hydrogen carbonates.

M is preferably the cation of sodium. potassium or most preferably calcium.

Both inorganic and organic polar solvents can be used as diluents for the reaction according to the invention. such as for example water, lower aliphatic alcohols of l to 4 carbon atoms. lower aliphatic nitriles such as acetonitrile. tetrahydrofuran. dioxane. dimethoxyethane. pyridine. dimethylformamide and the like.

The reaction according to the invention is carried out at a temperature of about 0 to about C. preferably 20 to about 35C.

In practice. the lactone or lactone salts are dissolved or suspended in the diluent. and this solution or suspension is then treated with an appropriate quantity of the amine. The formation of the imine or of the imine salt takes place in a weakly exothermic reaction and the final product is then isolated through conventional methods.

The imine salts l can also be prepared by the reaction of the free acids with amines.

The salts may be obtained in a subsequent step by conventional techniques or directly in the reaction of the lactone with the amine. lfabout 2 mols ofthe amine per mol of lactone are employed. the product will be in the form of that amine salt. If an alkali metal salt or al kaline earth metal salt of the lactone is employed. or if it is desired to obtain the free acid from the lactone. only about 1 mol of the amine per mol of the lactone or salt is required.

The course of the process according to the invention can thus be illustrated by the following equations:

O 0 l t l C-OH i l O OH +3 0 O A coon 9 a s O}! C00 .2 l j /N\ on. N CH li NCCll3 J l, on l Cll=N-C-Cll. J 0 Cll3 I The following examples will serve to further typify are obtained in the form of yellow crystals which after he na re of his in enti n without being a limitation recrystallisation from acetonitrile/water melt at 228C. on the scope thereof. with decomposition.

EXAMPLE I 23.4 g (0.! mol) of l-oxo-3-hydroxy-l.3-dihydrotarot3,4b)-quino:raline-4,9-dioxide are suspended in g'gfili lffiflt 'fil lifflj'K5911}'" 60 ml of water and 20 g (0.2 mol) of 60 percent Found: 1.7m Ht 't ts l3.5i Naofii strength aqueous isopropylamine solution are added. The temperature is kept below 30C by slight cooling. After a few minutes, a clear solution is produced. Evap- T 'l i 3- oration in vacuo yields 45 g ofthe compound ofthe forlu'"(lxillmeAB-dmxlde the fumlulil (l1 f l m the starting compound can be obtained as follows:

0 30.7 g (0.] mol) of Z-bismethoxy-mcthyl-J- T G) G) /CH dimethylaminocarbonyl-quinoxnline-l,4-di-N-oxide N coo are introduced into I00 ml of lOpcrcentstrength aque- 3 \CH ous hydrochloric acid. A clear solution results. and I H after a short time the compound according to the in- H vention separates out in the form of a yellow precipi- 3 tate, which is filtered ofl'atter 6 hours. 17 g (72.6 percent of theory) of loxo-3-hydroxy-l.3-dihydro-turoin the form ofyellow crystals, which after recrystallisaqulnoxflllne'4ig'dloxlde are lhus blamed m tion from isopropanol melt at 12325C. with decomthe form of yellow l' I position. The compound is purified by dissolving it in sodium bicarbonate solution, filtering and acidifying the fily i O s O Analysis: cmHflNodmolecular weight 334) trate The purified compound melts at l- 6 l. 9 C. Calculated: 57 H N mm whilst foaming. Found; C $7M; H s 8% N 168% EXAMPLE 2 q analysis: (t gl'l li osivl l w I, 27.4 g (0.] mol) of the Na salt of Z-(di-hydroxyfifjffifilf 3 is: F: i52

methyl)3-carboxylic acid-quinoxaline-di-N-oxide are dissolved in ml of water and 7.3 g (0.l mol) of tert.-butylamine are added. The temperature is kept at The alkali metal salts or alkaline earth metal salts of 25C by cooling. After l hour, the solution is evapol-oxo-3-hydroxy-l.3-dihydro-furo-(3.4-b)-quinoxarated in vacuo and 32 g of the compound of the forline-4,9-dioxide can be manufactured as follows: mula The lactone (9) is suspended in water and approxi- 0 mately the stoichiometrically required amount of the 1 alkali metal hydrogen carbonate or alkaline earth metal COQN M hydrogen carbonate is added at room temperature. The salt of the lactone IU). thus produced, precipitates. 5 after evaporation of the solution it necessary. and can CH:N--C--Ci-l be isolated in the usual manner. J, E 3 The following are obtained analogously to Examples 0 3 l and 2:

Cormound Exarnolr. 1 0.

I n cn= 0 T 6 69 85-85 (decomposi N CCO HSBFC HS tion) COOK R-0 1?.

106 (decomposition) 138-40 (deco:

:osition 128-30 (dcoonpo i tier.)

9 6) 117-18 (dccomyosi ion) Co."- :1 r5

l6 @HICOONa u 1 CH N N a 02 l8 @NICOOIQ.

. 2 cum-wmc-rm 200 (dccozgcsiticn) 2'10 (decomposition) 262 (decomposition) 230 (deccnpasition) 1'79 (decozposition) 21 5 :12? ffo Con-roux".

ll CH=N-II'H- COOC H As has already been mentioned, the new compounds of the invention surprisingly show an excellent chemotherapeutic activity. Their chemotherapeutic action was examined both in animal experiments (oral and subcutaneous administration) with acute bacterial infections, and in vitro. In both cases the compounds show a very good antibacterial action, and the range of action encompasses both Gram-negative and Grampositive bacteria. The chemotherapeutic activity ofthe compounds according to the invention permits their use in human medicine and in veterinary medicine. Furthermore, the compounds can be employed as feedstuff additives. especially in raising young animals or fatstock. The good in vitro and in vivo activity of the compounds according to the invention can be seen from Tables I, 2 and 3 below.

The minimum inhibitory concentrations in vitro for some of the new compounds shown in Table l (MIC) were determined by the plate test in an agar medium of the following composition:

proteose peptone HM) g per litre veal extract (solids) i0.(l g do. dextrose 2,0 g do. sodium chloride 3.0 g do. disodium phosphate 2.0 g do. sodium acetate Lt) g do. adenine sulphate 0.0] g do. guanine hydrochloride 0.0] g do. uracil (Mil g do. xanthin 0.0! g do. neutral agar I2.U g do.

@ii coon I u ca=a-imcooca cii oa 209 (decomposition) 21 2413 (decomposition) 156-151 (decomposition) 5.10 X 10" germs were inoculated per plate. Readings were taken after 24 and 48 hours, and the incubation temperature was about 37C.

Table l MIC in ylml of medium Minimum inhibitory concentration (MIC) in y/ml of medium, measured by the series dilution test (complete medium). incubation temperature: 37C. determination of the MIC after I8, 24 and 48 hours.

Compound of Bacterium Example I3 .SIreplmm'uo' filt'llI/l) ATCC 9700 50 do. do. 8564 IOU do. do. 8580 50 do. do. 8698 100 do. do. 8699 100 do. do. SH 1 50 .Slreplm'octm' fuer'ulii ATCC' E.Ht I

do. do. Blaschke 6-25 do. do. I3 25 do. do. species I00 do. do. liquef. 50 do. do. durans 25 list lu'rlclu'a mlr' C I65 0-]00 do. 2 -50 do. 55 B 5 3-6 do. 14 12-25 do. A 26l 25-50 do. l83/58 6l 2 Prawns miruhiltr G 12 do. 2935 i2 do. rnlgariir 3400 50 d0. [U17 l7 lsendmnunus aeruginuxu W 400 do. M 25 do. B 25 Klebsiella ATCC I003l l-2 do. K IU 50 do. 63 50 Salmonella paraIyp/u'i B8 ll 12 ('m rnebucterium dip/Ue'ria grut'is 5-10 .S'rruplrvlmmrus uureus 13 I do. 7705 12 do. BRL l2 Nr'issr'riu cur/rural! N [Mi 6 Myer/plasma gulliu'nlirum 6 Mytuplmmu gulliscpricum "'l 6 do. grunularum "J 3 Mrt'uhm'mrimn tuberculosis H 37 RV 40 For the compound of Example 3. the following minimal inhibitory concentrations (MIC) (y/ml of nutrient medium) were measured by the series dilution test (PPLO medium). incubation temperature 37C. determination after 18. 24 and 48 hours.

Bacterium MIC M \t'vpld.tlllll gallisrplirum I00 do. g anulurum 25 do hr)tiV/Iilli.t 200 mal or patient or on the nature ofthc method ofadministration, but also because of the type of animal and its individual behaviour towards the medicament. or because ofthe nature ofthe formulation ofthe latter. and the point in time or interval at which administration takes place. Thus it can. in some cases. suffice to use less than the abovementioned minimum amount. whilst in other cases the upper limit mentioned must be exceeded. In the case of the administration of larger amounts it can be advisable to divide these into several individual doses over the course of the day. The same range of dosages is envisaged for administration in human medicine. The other comments made above also apply in a general sense.

Accordingly, the present invention provides a pharmaceutical composition containing as an active ingredient at least one of the new compounds ofthe general formula (1) given above in admixture with a pharmaceutically acceptable solid or liquid diluent or carrier as hereinafter define.

ln the present specification the expression pharmaceutically acceptable diluent or carrier means a nontoxic substance that when mixed with the active ingredient or ingredients renders it suitable for administration. The expression preferably excludes water and low-molecular weight organic solvents commonly used in chemical synthesis, except in the presence of other pharmaceutically necessary ingredients such as salts in correct quantities to render the composition isotonic. buffers, surfactants. colouring and flavouring agents, and preservatives. Examples of suitable liquid diluents and carriers are vegetable oils. glycerol. propylene glycol. polyols. buffered aqueous solutions. isotonic saline aqueous solutions, syrups and lotion bases. Examples of suitable solid diluents and carriers are starches. cellulose and its derivatives, sugars. stearates and stearic acid. talc. and ointment bases. Examples of pharmaceutical compositions according to the invention are ointments. pastes. creams. sprays. lotions. aqueous and non-aqueous suspensions. emulsions, and solutions (including parenterally injectable solutions). elixirs and syrups. and granulates and powders either freeflowing or compressed into tablets.

Pharmaceutical compositions of the invention adapted for oral administration are a preferred embodiment of the invention. The diluents and carriers used are preferably therefore those that adapt the active ingredient or ingredients for oral administration. Examples of such diluents and carriers are solid vehicles. excipients and lubricants such as glucose. lactose and su- In general. it has proved advantageous. in acute general infections. to administer amounts of about 5 mg to about 200 mg per kilogram. preferably about 25 to about 50 mg per kilogram of body weight per day, to achieve effective results. Nevertheless it can at times be necessary to deviate from the amounts mentioned. in particular depending on the body weight of the test anicrose. corn and potato starch. sodium carboxymethylcellulose, ethyl cellulose and cellulose acetate. powdered gum tragacanth. gelatin. alginic acid. agar. talc. stearic acid and sodium. calcium and magnesium stearates. sodium lauryl sulphate. poIyvinyl-pyrollidone. sodium citrate. calcium carbonate, and dicalcium phosphate.

The pharmaceutical compositions of the invention may also contain other non-toxic adjuvants and modifiers such as dyes. surfactants. perfumes, flavouring agents. such as sweeteners. preservatives and biocides.

Pharmaceutical compositions of the invention adapted for parenteral injection are another preferred embodiment of the invention. The diluents and carriers used are therefore preferably those that adapt the active ingredient for parenteral administration. Examples of diluents and carriers that adapt the active ingredient for parenteral administration are solvents and suspending diluents such as water. vegetable fatty oils. such as sesame oil. groundnut oil. corn oil. and cottonseed oil, aqueous propylene glycol, N,N' dimethylformamide. and dimethyl sulphoxide. In general. any non-aqueous diluent can be used that does not reduce the activity of the active ingredient and is non-toxic in the dose employed.

For the administration of the water-soluble compounds of the invention by parenteral injection sterile aqueous solutions can be employed. and are within the scope of the pharmaceutical compositions of the invention. Such aqueous solutions should preferably when necessary be buffered in the usual manner. and the liquid diluent should preferably before administration be rendered isotonic by adding the requisite amount of salt or glucose. Such sterile buffered isotonic solutions are especially suitable for intravenous, intramuscular and intraperitoneal injections. These pharmaceutical compositions of the invention can further contain local anaesthetics or substances that promote the diffusion of the active ingredient. for example hyaluronidase.

The pharmaceutical compositions of the invention preferably contain 0.5 to 90 wt. percent of at least one new compound of the invention.

The present invention also provides medicaments in dosage unit form as hereinafter defined comprising as an active ingredient at least one compound of general formula (1 given above either alone or in admixture with a pharmaceutically acceptable solid or liquid diluent or carrier. In this case the diluent or carrier is preferably as defined above but can also be water or another common solvent.

The expression medicament in dosage unit form as used in the present specification means a medicament in the form of discrete portions each containing a unit dose or a multiple or sub-multiple of a unit dose of the active ingredient(s); for example. one. two. three or four unit doses or a half. a third or a quarter of a unit dose. A "unit dose" is the amount of the active ingredient( s) to be administered on one occasion and will usually be a daily dose. or for example a half. a third. or a quarter of a daily dose depending on whether the medicament is to be administered once or. for example. twice, three times. or four times a day.

The discrete portions constituting the medicament in dosage unit form can include a protective envelope. The active ingredient can be undiluted and contained in such an envelope. or can be mixed with a pharmaceutically acceptable solid or liquid diluent or carrier as defined above. Such portions can for example be in monolithic coherent form. such as tablets. lozenges. pastilles. pills. suppositories. or dragees; in wrapped or concealed form, the active ingredients being within a protective envelope. such as wrapped powders. cachets. sachets, capsules, or ampoules; or in the form of a sterile solution suitable for parenteral injection. such as ampoules of buffered. isotonic. sterile. pyrogen-free aqueous solution; or in any other form known in the art.

As stated above, peroral administration is a preferred mode of administration. Preferred medicaments in dosage unit form according to the invention are therefore those adapted for oral administration. such as tablets. pills. dragees. capsules. and cachets, as well as wrapped powders containing the active ingredient in powdered form with a powdered diluent or carrier for suspension in water before being taken.

As also stated above a further preferred mode of administration is parenteral administration. Preferred medicaments in dosage unit form according to the invention are therefore those adapted for parenteral injection, such as ampoules containing a measured quantity of a sterile isotonic saline injectable aqueous solution of the new active ingredient, which may be buffered with a pharmaceutically acceptable buffer and are preferably free of pyrogens.

The preferred unit dose for administration of the medicaments of the invention is 250 l6.000 mg. of active ingredient. preferably L250 4.000 mg. This will usually be administered once daily.

The invention further provides a method of combatting bacterial infection in an animal which comprises administering to the animal (preferably parenterally or perorally} an effective amount of one of the new compounds. either alone, as a pharmaceutical composition according to the invention. or as a medicament in dosage unit form according to the invention.

Indications envisaged in human medicine are especially general infections. and infections of the efferent urinary tract. caused by Gram-positive and Gramnegative bacteria and by mycoplasma. and in veterinary medicine are general infections caused by Gram negative and Gram-positive bacteria and by mycoplasma. Infections of the respiratory passages in poultry, especially in chicks. and mastitis of cows. may be mentioned particularly.

The new compounds can. as has already been mentioned. also be employed as a feedstuff additive. predominantly in raising young animals, especially chicks and fatstock.

The preparations can be administered in the feedstuff. special feedstuff preparations and feedstuff concentrates. but also via the drinking water.

The invention therefore also provides animal feedstul'fs and feedstuff concentrates containing at least one of the new compounds of general formula (1 J.

The administration of the new compounds together with the feedstuff or feedstuff preparations and/or with the drinking water makes it possible to prevent or treat infections by both Gram-negative and Gram-positive bacteria and mycoplasma. and can furthermore contribute to better utilisation of the feedstuff. As examples of frequently occurring veterinary illnesses which cause considerably economic damage and which can be prevented or treated by administering the new compounds in the feedstuff or in the drinking water. there may be mentioned. in addition to general infections. infection of the air sac in chicks. and mastitis in cows.

What is claimed is:

l. A compound of the formula or a pharmaceutically acceptable non-toxic salt thereof wherein Y is hydrogen, an alkali metal cation or the cation R"N*H and each of R and R" is in which X is O, S or NH, and

each of R and R when taken independently is identical to or different from the other, and is selected from the group consisting of hydrogen, alkyl of l to 4 carbon atoms and hydroxyalkyl of l to 4 car or a pharmaceutically acceptable non-toxic alkali metal or alkaline earth metal salt thereof.

9. The compound according to claim 1 which is 10. The compound according to claim I which is @NYOORH N/ cn=nsiacon o i bon atoms, or R and R together with the nitrogen atom to which they are attached form a morpholino or S,S-dioxothiomorph0lino ring.

2. A compound according to claim 1 wherein R and R are hydrogen or alkyl of l to 4 carbon atoms or R' and R together with the nitrogen atom to which they are attached form a morpholino or S,S-dioxothiomorpholino ring.

3. A compound according to claim 1 wherein Y is hydrogen.

4. A compound according to claim I wherein Y is a sodium or potassium cation.

5. A compound according to claim 1 wherein X is O. 4O

12. The compound according to claim I which is 6. A compound according to claim I wherein X is S. 7. A compound according to claim 1 wherein X is 8. The compound according to claim I which is OONa 

1. A COMPOUND OF THE FORMULA
 2. A compound according to claim 1 wherein R1 and R2 are hydrogen or alkyl of 1 to 4 carbon atoms or R1 and R2 together with the nitrogen atom to which they are attached form a morpholino or S,S-dioxothiomorpholino ring.
 3. A compound according to claim 1 wherein Y is hydrogen.
 4. A compound according to claim 1 wherein Y is a sodium or potassium cation.
 5. A compound according to claim 1 wherein X is O.
 6. A compound according to claim 1 wherein X is S.
 7. A compound according to claim 1 wherein X is NH.
 8. The compound according to claim 1 which is
 9. The compound according to claim 1 which is
 10. The compound according to claim 1 which is
 11. The compound according to claim 1 which is
 12. The compound according to claim 1 which is 